Adds an alpha-D-arabinofuranosyl group from trans,octacis-decaprenylphospho-beta-D-arabinofuranose at the 3-O-position of an alpha-(1->5)-arabinofuranan chain attached to a beta-(1->5)-galactofuranan chain

the enzyme introduces alpha-(1->3) branch points in the internal arabinan domain in both arabinogalactan and lipoarabinomannan synthesis. The enzyme can only transfer D-arabinofuranose when a minimum of three arabinofuranosyl residues are present in a linear structure in order to introduce an alpha-D-Araf-(1->3) branch point

no activity with octyl alpha-D-Araf-(1->5)-alpha-D-Araf and dipalmitoyl phosphatidylcholine, the enzyme introduces alpha-(1->3) branch points in the internal arabinan domain in both arabinogalactan and lipoarabinomannan synthesis. The enzyme can only transfer D-arabinofuranose when a minimum of three arabinofuranosyl residues are present in a linear structure in order to introduce an alpha-D-Araf-(1->3) branch point